Field
Aspects of the present invention relate to a light emitting diode (LED) platform or other solid state light emitter light devices.
Background of the Technology
LEDs or other similar solid state light emitters provide an energy efficient alternative to incandescent, fluorescent, High Intensity Discharge (HID) and halogen lighting.
One type of LED lighting sources is a chip-on-board (COB) LED lighting source. COB LED technology includes a large number of LED semiconductor devices (or dies) mounted in direct contact with or produced on a substrate to produce LED arrays. Thus, COB light assemblies generally include multiple LED chips packaged together into one lighting module forming a large effective emitting surface. It gives the appearance of a more extended light source when compared to single die LEDs that approximate a point source. COB LEDs have a number of advantages over traditional surface mount technologies such as “T-pack” and Surface mounted LEDs. Due to the small size of the LED chip, COB LEDs allow for a much higher packing density than surface mount technology, thereby enabling higher intensity and greater uniformity of light emission.
Although these COB, or cluster LEDs, provide increased light intensity and uniformity, they bring the challenge of added heat generation into a smaller or more focused area. Even though LED lights generate less heat than traditional lights, these lights still emit heat that needs to be dissipated from the interior of the housing, heat sink, or light engine package. If the heat is not efficiently removed, test data has shown the lifetime of the light emitting component will be significantly shortened. In order to create efficient thermal pathways for the heat to be removed, various openings may be required and the addition of fins may be placed on the housing design and construction. While various openings are created and adding heat sink fins may allow heat to escape, their net effect may be to also allow debris material and moisture to collect on and even enter the housing area. Once debris collects in such fins, they can become clogged and may not function as designed to remove heat from the lamp. For example, if birds land on the light and leave droppings, over time this can result in clogging such fins, and the fins may no longer function to dissipate heat according to their intended design.
FIGS. 1A-D illustrate an Evolve® LED roadway lighting fixture manufactured by GE®, which include fins on the upper portion of the housing. These fins may become clogged due to bird droppings, dust, and other debris depending on the application. Once clogged, the ability to dissipate heat is diminished, thereby shortening the life of the light emitters.
In order to increase the amount of emitted light, additional LED units or light engines may be added. This requires additional housing structure to be designed around the LED engines. Housing structure typically surrounds the entire light assembly. As the housing is extended in various designs, debris, such as dust, animal debris, insect nest habitats, etc. and snow and ice in winter months is more prone to build up on the upper portion of the housing. As the LED light engine does not generally heat the upper housing area to the same degree as incandescent or high discharge lamps, during periods of heavy moisture in winter months, snow and ice may tend to build up and not be able to melt in a timely manner. The added weight from the snow and ice can damage the light, or because of additional load, cause the light to break off from the pole where it is mounted. The LED light assembly, depending upon the size and model, as mounted and extending from a pole is already heavy. As such, a boom or mount holding this LED light must be sturdy enough to handle this weight. The addition of collected snow and ice can cause the already heavy light to break. In order to avoid such damage, a boom must be constructed even more solidly to be able to handle the potential for additional weight. This incurs manufacturing costs, and most customers do not wish to incur the additional costs into the replacement of the lights. Further, lights with snow and ice build-up that break off have the potential to cause damage and accident to pedestrians and traffic below the lights.
FIG. 1A illustrates a fixture having a single light engine, FIG. 1B illustrates a fixture having two light engines, FIG. 1C illustrates a fixture having three light engines, and FIG. 1D illustrates a fixture having four light engines. In order to increase the number of light engines, the outer housing that surrounds the light engines must be built larger, adding weight, and as such the number of square inches of space on top of the light also increases. As the housing size increases, the ability to collect snow, ice, and other debris on the upper portion also increases. Thus, a boom holding the light fixture must be manufactured in a manner to securely hold the added weight from the added LED light engines, the added housing, and to account for the possibility of additional weight from snow and ice collection. Otherwise, the light fixture may break when additional weight of the frozen moisture collects on it.
Similarly, FIGS. 2A and 2B illustrate a Neptun® parking lot LED fixture. The LED fixture extends from a boom to illuminate a large area such as a roadway or parking lot. FIG. 2B shows the LED fixture having double the LED light engines of FIG. 2A. In order to double the number of light engines, the outer housing doubles in size and results in a proportional increase in the space on top of the light. Again, this can double or exponentially increase the amount of weight that must be handled by the boom extending from a pole to hold the light fixture. With the upper portion of the housing area increasing, this enables additional snow and ice and other bird residue to collect on top of the housing.